Research On Interface Behavior And Mechanical Properties Of Diffusion Bonding Between Glass And Metal Assisted By Vacuum Electric Field

With the development of electronics,aviation,aerospace and other fields,the connection of glass to metal,and glass to semiconductor has been widely used.Due to the huge difference in physical and chemical properties between glass and metal,it is difficult to achieve a reliable connection.Therefore,it is an urgent problem to find a way to connect glass and metal.Anodic bonding is a solid electrochemical reaction process,which is often applied to the connection of glass and metal,and glass and semiconductor.It was proposed by Wallis of the United States as early as the 1960s.After decades of development,it is now one of the important technologies for the connection of glass and metal in the manufacturing process of micro electro mechanical systems(MEMS)packaging.In this paper,anodic bonding is used to realize the glass-Kovar connection,focusing on the analysis of the changing law of the bonding current and the formation mechanism of the bonding interface.And on this basis,the Kovar-Glass-Si three-layer wafer connection was successfully realized by a two-step anodic bonding process,and the current change law was analyzed by establishing a current model.At the same time,anodic bonding is used to connect the glass and the aluminum foil,so that the surface of the glass is metalized.Then,diffusion bonding was used to successfully realize the connection between glass and titanium.And by analyzing the interface changes with different annealing times,the evolution mechanism of the bonding interface is analyzed.The results of the study are as follows:(1)The glass-Kovar is successfully connected through anodic bonding.From the time-current change rule during the bonding process,it can be seen that as the bonding voltage and temperature increase,the peak bonding current is also increasing.The area of the bonding interface increases.The tensile test results show that as the bonding voltage and temperature increase,the mechanical properties of the Glass-Kovar joints are also improving,and the fracture of the bonded sample always occurs on the glass substrate.(2)For the anodic bonding of Kovar-Glass-Si three-layer wafers connected by a two-step anodic bonding process,the first and second bonding currents have the same changing law,and both increase with the increase of the bonding voltage.However,the peak value of the bonding current in the second step is always greater than that in the first step.And using SEM to observe the corroded Kovar-Glass-Si interface,it is found that there is a sodium ion depletion layer at the Kovar-Glass and Glass-Si interface,and the depletion layer appears as the bonding voltage increases.The thickness is increasing.(3)The anodic bonding and diffusion bonding composite method is used to realize the connection of Glass-Ti.First,the current variation and mechanical properties of Glass-Al under different parameters are studied,and the thickness of the Na⁺depletion layer at the Glass-Al interface is 500nm at 450?/800V.Then the changes of the microscopic morphology and element distribution of the Glass-Al-Ti interface under different annealing times are studied.First,Ti Al₃ phase is formed at the aluminum-titanium interface,then as the annealing time increases,the Si element in the glass also diffuses.And it dissolves into the Ti Al₃ phase.With the increase of Si element,the solubility of Ti Al₃ reaches saturation,and a new phase Ti Si₂ is formed in the diffusion layer.It is also found that the content of Si element and Al element is inversely proportional.